The National Republican Senatorial Committee, meanwhile, raised just over $5 million in March and has $16.5 million cash on hand, committee officials said Wednesday. It has raised $50.4 million in the 2005-06 cycle.

It's rare for Democrats to have an ongoing cash advantage over Republicans, especially as the Republican National Committee maintains its dominance.

The RNC raised $10.9 million in March - $35 million in the first quarter of the year - and has almost $43 million in the bank. The Democratic National Committee, meanwhile, raised $18 million in the first quarter and has $10.5 million on hand.

GOP strategists have said the RNC will have enough money to help the Senate committee if necessary on efforts such as voter turnout.

The GOP holds a 55-44 advantage in the Senate, with one Democratic-leaning independent.